U.S. patent application number 15/687238 was filed with the patent office on 2017-12-28 for optical line terminal (olt) support of optical network unit (onu) calibration.
This patent application is currently assigned to Futurewei Technologies, Inc.. The applicant listed for this patent is Futurewei Technologies, Inc.. Invention is credited to Bo GAO, Jianhe GAO, Dekun LIU, Yuanqiu LUO, Xuming WU.
Application Number | 20170373786 15/687238 |
Document ID | / |
Family ID | 54931683 |
Filed Date | 2017-12-28 |
United States Patent
Application |
20170373786 |
Kind Code |
A1 |
WU; Xuming ; et al. |
December 28, 2017 |
Optical Line Terminal (OLT) Support of Optical Network Unit (ONU)
Calibration
Abstract
An optical line terminal (OLT) channel termination (CT)
comprises a receiver configured to receive an upstream message
which comprises a correlation tag from an optical network unit
(ONU), wherein the correlation tag represents a unique number, a
processor coupled to the receiver and configured to process the
upstream message, and generate a downstream message based on the
upstream message, wherein the downstream message comprises the
correlation tag, and a transmitter coupled to the processor and
configured to transmit the downstream message to the ONU.
Inventors: |
WU; Xuming; (Wuhan, CN)
; LIU; Dekun; (Wuhan, CN) ; LUO; Yuanqiu;
(Cranbury, NJ) ; GAO; Jianhe; (Wuhan, CN) ;
GAO; Bo; (Wuhan, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Futurewei Technologies, Inc. |
Plano |
TX |
US |
|
|
Assignee: |
Futurewei Technologies,
Inc.
Plano
TX
|
Family ID: |
54931683 |
Appl. No.: |
15/687238 |
Filed: |
August 25, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14713550 |
May 15, 2015 |
9768905 |
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15687238 |
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62016852 |
Jun 25, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04J 14/0252 20130101;
H04B 10/272 20130101; H04J 14/0221 20130101; H04B 10/0773 20130101;
H04J 14/0223 20130101; H04J 14/0282 20130101; H04B 10/0775
20130101 |
International
Class: |
H04J 14/02 20060101
H04J014/02; H04B 10/272 20130101 H04B010/272; H04B 10/077 20130101
H04B010/077 |
Claims
1. An optical line terminal (OLT) channel termination (CT)
comprising: a receiver configured to receive an upstream message
from an optical network unit (ONU), wherein the upstream message
comprises a correlation tag, wherein the correlation tag represents
a unique number; a processor coupled to the receiver and configured
to generate a downstream message based on the upstream message,
wherein the downstream message comprises the correlation tag; and a
transmitter coupled to the processor and configured to transmit the
downstream message to the ONU.
2. The OLT CT of claim 1, wherein the correlation tag comprises a
first value which differentiates the ONU from other ONUs, and
wherein the first value changes to a second value when the ONU
tunes at least one of wavelength and power of upstream optical
signals.
3. The OLT CT of claim 2, wherein the downstream message further
comprises a calibration identification (ID), and wherein the
calibration ID comprises "0" bits and a calibration status bit.
4. The OLT CT of claim 3, wherein the calibration status bit has a
first binary value indicating the ONU should continue calibration,
wherein the calibration status bit has a second binary value
indicating the ONU should be activated, and wherein the first
binary value and the second binary value are different.
5. The OLT CT of claim 4, wherein the downstream message further
comprises an upstream wavelength channel ID, wherein the upstream
wavelength channel ID indicates the wavelength channel in which the
upstream wavelength is being calibrated when the calibration status
bit has the first binary value, and wherein the upstream wavelength
channel ID indicates the wavelength channel which is ready for
activation when the calibration status bit has the second binary
value.
6. The OLT CT of claim 5, wherein the downstream message further
comprises a received signal strength indicator (RSSI), and wherein
the RSSI indicates optical power received from the ONU at the OLT
CT.
7. The OLT CT of claim 6, wherein the upstream message and the
downstream message are physical layer operation, administration and
maintenance (PLOAM) messages.
8. An optical network unit (ONU) comprising: a transmitter
configured to transmit an upstream message to an optical line
terminal (OLT) channel termination (CT), wherein the upstream
message comprises a correlation tag, wherein the correlation tag
represents a unique number; and a receiver coupled to the
transmitter and configured to receive a downstream message from the
OLT CT, wherein the downstream message comprises the correlation
tag.
9. The ONU of claim 8, wherein the correlation tag comprises a
first value which differentiates the ONU from other ONUs, and
wherein the first value changes to a second value when the ONU
tunes at least one of wavelength and power of upstream optical
signals.
10. The ONU of claim 9, wherein the downstream message further
comprises a calibration ID, and wherein the calibration ID
comprises "0" bits and a calibration status bit.
11. The ONU of claim 10, wherein the calibration status bit has a
first binary value indicating the ONU should continue calibration,
wherein the calibration status bit has a second binary value
indicating the ONU should be activated, and wherein the first
binary value and the second binary value are different.
12. The ONU of claim 11, wherein the downstream message further
comprises an upstream wavelength channel ID, wherein the upstream
wavelength channel ID indicates the upstream wavelength channel in
which the upstream wavelength is being calibrated when the
calibration status bit has the first binary value, and wherein the
upstream wavelength channel ID indicates the upstream wavelength
channel which is ready for activation when the calibration status
bit has the second binary value.
13. The ONU of claim 12, wherein the downstream message further
comprises a received signal strength indicator (RSSI), and wherein
the RSSI indicates received optical power at the OLT from the
ONU.
14. The ONU of claim 13, wherein the upstream message and the
downstream message are physical layer operation, administration and
maintenance (PLOAM) messages.
15. A method for optical network unit (ONU) online calibration,
comprising: receiving an upstream message from an ONU, wherein the
upstream message comprises a correlation tag, wherein the
correlation tag represents a unique number; generating a downstream
message based on the upstream message, wherein the downstream
message comprises the correlation tag; and transmitting the
downstream message to the ONU.
16. The method of claim 15, wherein the correlation tag comprises a
first value which differentiates the ONU from other ONUs, and
wherein the first value changes to a second value when the ONU
tunes at least one of wavelength and power of upstream optical
signals.
17. The method of claim 16, wherein the downstream message further
comprises a calibration ID, wherein the calibration ID comprises
"0" bits and a calibration status bit, wherein the calibration
status bit has a first binary value indicating the ONU should
continue calibration, wherein the calibration status bit has a
second binary value indicating the ONU should be activated, and
wherein the first binary value and the second binary value are
different.
18. The method of claim 17, wherein the downstream message further
comprises an upstream wavelength channel ID, wherein the upstream
wavelength channel ID indicates a wavelength channel in which the
upstream wavelength is being calibrated when the calibration status
bit has the first binary value, and wherein the upstream wavelength
channel ID indicates the wavelength channel which is ready for
activation when the calibration status bit has the second binary
value.
19. A method for optical network unit (ONU) online calibration,
comprising: transmitting an upstream message to an optical line
terminal (OLT) channel termination (CT), wherein the upstream
message comprises a correlation tag, wherein the correlation tag
represents a unique number; and receiving a downstream message from
the OLT CT, wherein the downstream message comprises the
correlation tag.
20. The method of claim 19, wherein the correlation tag comprises a
first value which differentiates the ONU from other ONUs, and
wherein the first value changes to a second value when the ONU
tunes at least one of wavelength and power of upstream optical
signals.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. provisional patent
application No. 62/016,852 filed Jun. 25, 2014 by Xuming Wu, et
al., and titled "Optical Line Terminal (OLT) Support of Optical
Network Unit (ONU) Calibration," which is incorporated by reference
in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
[0003] Not applicable.
BACKGROUND
[0004] A passive optical network (PON) is one system for providing
network access over the last mile, which is the final portion of a
telecommunications network that delivers communication to
customers. A PON is a point-to-multipoint (P2MP) network comprised
of an optical line terminal (OLT) at a central office (CO), an
optical distribution network (ODN), and optical network units
(ONUs) at the user premises. PONs may also comprise remote nodes
(RNs) located between the OLTs and the ONUs, for instance at the
end of a road where multiple customers reside.
[0005] In recent years, time-division multiplexing (TDM) PONs such
as gigabit-capable PONs (GPONs) and Ethernet PONs (EPONs) have been
deployed worldwide for multimedia applications. In TDM PONs, the
total capacity is shared among multiple users using a time-division
multiple access (TDMA) scheme, so the average bandwidth for each
user may be limited to below 100 megabits per second (Mb/s).
[0006] Wavelength-division multiplexing (WDM) PONs are considered a
very promising solution for future broadband access services. WDM
PONs can provide high-speed links with dedicated bandwidth up to 10
gigabits per second (Gb/s). By employing a wavelength-division
multiple access (WDMA) scheme, each ONU in a WDM PON is served by a
dedicated wavelength channel to communicate with the CO or the OLT.
Next-generation PONs (NG-PONs) and NG-PON2s may include
point-to-point WDM PONs (P2P-WDM PONs), which may provide data
rates higher than 10 Gb/s.
[0007] NG-PONs and NG-PON2s may also include time- and
wavelength-division multiplexing (TWDM) PONs, which may also
provide data rates higher than 10 Gb/s. TWDM PONs may combine TDMA
and WDMA to support higher capacity so that an increased number of
users can be served by a single OLT with sufficient bandwidth per
user. In a TWDM PON, a WDM PON may be overlaid on top of a TDM PON.
In other words, different wavelengths may be multiplexed together
to share a single feeder fiber, and each wavelength may be shared
by multiple users using TDMA.
SUMMARY
[0008] In one embodiment, the disclosure includes an OLT channel
termination (CT) comprising a receiver configured to receive an
upstream message which comprises a correlation tag from an ONU,
wherein the correlation tag represents a unique number, a processor
coupled to the receiver and configured to process the upstream
message, and generate a downstream message based on the upstream
message, wherein the downstream message comprises the correlation
tag, and a transmitter coupled to the processor and configured to
transmit the downstream message to the ONU.
[0009] In another embodiment, the disclosure includes an ONU
comprising a transmitter configured to transmit an upstream message
to an OLT CT, wherein the upstream message comprises a correlation
tag, wherein the correlation tag represents a unique number, and a
receiver coupled to the transmitter and configured to receive a
downstream message from the OLT CT, wherein the downstream message
comprises the correlation tag.
[0010] In yet another embodiment, the disclosure includes a method
for ONU online calibration, comprising receiving an upstream
message from an ONU, wherein the upstream message comprises a
correlation tag, wherein the correlation tag represents a unique
number, generating a downstream message based on the upstream
message, wherein the downstream message comprises the correlation
tag, and transmitting the downstream message to the ONU.
[0011] In yet another embodiment, the disclosure includes another
method for ONU online calibration, comprising transmitting an
upstream message to an OLT CT, wherein the upstream message
comprises a correlation tag, wherein the correlation tag represents
a unique number, and receiving a downstream message from the OLT
CT, wherein the downstream message comprises the correlation
tag.
[0012] These and other features will be more clearly understood
from the following detailed description taken in conjunction with
the accompanying drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For a more complete understanding of this disclosure,
reference is now made to the following brief description, taken in
connection with the accompanying drawings and detailed description,
wherein like reference numerals represent like parts.
[0014] FIG. 1 is a schematic diagram of a TWDM PON.
[0015] FIG. 2 is a message sequence diagram illustrating ONU online
calibration.
[0016] FIG. 3 is a flowchart illustrating a method for ONU online
calibration according to an embodiment of the disclosure.
[0017] FIG. 4 is a flowchart illustrating another method for ONU
online calibration according to an embodiment of the
disclosure.
DETAILED DESCRIPTION
[0018] It should be understood at the outset that, although
illustrative implementations of one or more embodiments are
provided below, the disclosed systems and/or methods may be
implemented using any number of techniques, whether currently known
or in existence. The disclosure should in no way be limited to the
illustrative implementations, drawings, and techniques illustrated
below, including the exemplary designs and implementations
illustrated and described herein, but may be modified within the
scope of the appended claims along with their full scope of
equivalents.
[0019] Prior PON technologies are single-wavelength PONs and employ
an OLT with a single OLT CT, which is an OLT port communicating
with ONUs. Therefore, the prior PON technologies do not support ONU
wavelength tuning. NG-PONs and NG-PON2s, including
multiple-wavelength PONs such as WDM PONs, P2P-WDM PONs, and TWDM
PONs may have multiple OLT CTs in order to support the multiple
wavelengths. Each OLT CT may provide data transmission in a pair of
upstream and downstream wavelengths. Upstream may refer to the
direction of communication from an ONU to the OLT. Downstream, on
the other hand, may refer to the direction of communication from
the OLT to the ONU.
[0020] In a typical TWDM PON, there may be up to eight wavelengths
in both the downstream direction and the upstream direction.
Calibration is a process of adjusting the wavelength of upstream
optical signals that an ONU transmits within a specific error
margin. Calibration may be necessary for an un-calibrated ONU or an
already-calibrated or pre-calibrated ONU that is experiencing
performance degradation. Offline calibration may refer to
calibration when an ONU is pre-calibrated before registering with a
PON. The ONU may know the wavelengths of all working upstream
wavelength channels and know how to calibrate itself to transmit in
a specific channel. Online calibration may refer to calibration
when the ONU must register with the PON in order to determine from
an OLT which upstream wavelength channel to use. The ONU may not
know the wavelengths of any working upstream wavelength channels or
know how to calibrate itself to transmit in a specific upstream
wavelength channel.
[0021] Existing standard draft, International Telecommunication
Union Telecommunication (ITU-T) Standardization Sector G.989.3
(draft ITU-T G.989.3) discloses a process for ONU online
calibration. After powering up, the ONU conducts downstream
scanning and calibration. The ONU chooses a downstream channel for
upstream channel calibration. The ONU learns the system and channel
profiles from the chosen downstream channel. As part of the
calibration, the ONU sends an upstream message to the OLT.
[0022] However, a direct response to the upstream message from the
OLT to the ONU is not provided in the draft ITU-T G.989.3.
Therefore, the ONU doesn't have enough information for online
calibration. For example, the ONU doesn't know if the upstream
wavelength of the ONU is correct, if the ONU needs to calibrate
more upstream wavelength channels, and if the ONU is ready to
activate the upstream wavelength channel for operation.
[0023] Disclosed herein are embodiments for online calibration of
an ONU. The ONU transmits an upstream message to an OLT CT, which
comprises a unique index number. The OLT CT receives the upstream
message and transmits a downstream message based on the upstream
message to the ONU, which comprises the unique index number. Both
the upstream message and the downstream message may be physical
layer operation, administration and maintenance (PLOAM) messages.
The disclosed embodiments are respect to a TWDM PON, but may also
apply to any PON supporting the ONU online calibration.
[0024] FIG. 1 is a schematic diagram of a TWDM PON 100. The TWDM
PON 100 may be suitable for implementing the disclosed embodiments.
The TWDM PON 100 may be a communications network that does not
require any active components to distribute data between an OLT 105
and ONUs.sub.1-n 150.sub.1-n. Instead, the TWDM PON 100 may use
passive optical components to distribute data between the OLT 105
and the ONUs.sub.1-n 150.sub.1-n. The TWDM PON 100 may adhere to
any standard related to multiple-wavelength PONs. The TWDM PON 100
comprises the OLT 105, a splitter 140, and the ONUs.sub.1-n
150.sub.1-n, where n may be any positive integer.
[0025] The OLT 105 may be any device configured to communicate with
the ONUs.sub.1-n 150.sub.1-n and another network. Specifically, the
OLT 105 may act as an intermediary between the other network and
the ONUs.sub.1-n 150.sub.1-n. For instance, the OLT 105 may forward
data received from the network to the ONUs.sub.1-n 150.sub.1-n, and
may forward data received from the ONUs.sub.1-n 150.sub.1-n to the
other network. When the other network uses a network protocol that
differs from the PON protocol used in the TWDM PON 100, the OLT 105
may comprise a converter that converts the network protocol to the
PON protocol. The OLT 105 converter may also convert the PON
protocol into the network protocol.
[0026] The OLT 105 may comprise a media access control (MAC) module
110, OLT CT.sub.1-m 115.sub.1-m, a wavelength multiplexer (WM) 120,
a wavelength demultiplexer (WDEM) 125, a local oscillator (LO) 130,
and a bi-directional optical amplifier (OA) 135. The MAC module 110
may be any module suitable for processing signals for use at a
physical layer in a protocol stack. The WM 120 may be any suitable
wavelength multiplexer, such as an arrayed waveguide grating (AWG).
The WM 120 may multiplex the wavelength channels and thus combine
the signals into a combined transmitted signal, then forward the
combined transmitted signal to the LO 130. The LO 130 may add
characteristics to the combined transmitted signal in order for the
ONUs.sub.1-n 150.sub.1-n to properly extract the signals. The LO
130 may then forward the combined transmitted signal to the OA 135,
which may amplify the combined transmitted signal as needed in
order to forward the combined transmitted signal to a splitter 140
via an optical fiber 137. The OA 135 may also receive a combined
received signal from the splitter 140 via the optical fiber 137 and
amplify the combined received signal as needed in order to forward
the combined received signal to the WDEM 125. The WDEM 125 may be
similar to the WM 120 and may demultiplex the combined received
signal into multiple optical signals, then forward the multiple
optical signals to the OLT CT.sub.1-m 115.sub.1-m.
[0027] The splitter 140 may be any device suitable for splitting
the combined optical signals and forwarding the split signals to
the ONUs.sub.1-n 150.sub.1-n. The splitter 140 may also be any
device suitable for receiving signals from the ONUs.sub.1-n
150.sub.1-n, combining those signals into a combined received
signal, and forwarding the combined received signal to the OA 135.
For example, the splitter 140 splits a downstream optical signal
into n split downstream optical signals in the downstream direction
(e.g. from the OLT 105 to the ONUs.sub.1-n 150.sub.1-n), and
combines n upstream optical signals into one combined upstream
optical signal in the upstream direction (e.g. from the
ONUs.sub.1-n 150.sub.1-n to the OLT 105).
[0028] The ONUs.sub.1-n 150.sub.1-n may be any devices suitable for
communicating with the OLT 105. The ONUs.sub.1-n 150.sub.1-n may
comprise wavelength tunable components 155.sub.1-n and MAC
modules.sub.1-n 160.sub.1-n. The wavelength tunable components
155.sub.1-n comprise wavelength tunable transmitters and wavelength
tunable filters (not shown). The MAC modules.sub.1-n 160.sub.1-n
are similar to the MAC module 110.
[0029] The TWDM PON 100 may provide WDM capability by associating a
downstream wavelength (e.g. .lamda.1d, .lamda.2d, . . . , and
.lamda.nd) and an upstream wavelength (e.g. .lamda.1u, .lamda.2u, .
. . , and .lamda.nu) with each OLT CT.sub.1-m, 115.sub.1-m so that
a plurality of wavelengths are present. The TWDM PON 100 may then
combine those wavelengths into a single optical fiber 137 and
distribute the wavelengths to the ONUs.sub.1-n 150.sub.1-n through
the splitter 140. The TWDM PON 100 may provide TDM as well.
[0030] FIG. 2 is a message sequence diagram 200 illustrating ONU
online calibration. The TWDM PON 100 of FIG. 1 may implement the
ONU online calibration. The diagram 200 illustrates messages
exchanged between an OLT CT 210 and an ONU 220. The OLT CT 210 and
the ONU 220 may be any OLT CT.sub.1-m 115.sub.1-m and any
ONU.sub.1-n 150.sub.1-n.
[0031] The ONU 220 initializes and calibrates its receiver and
transmitter (not shown). Initialization may comprise
self-configuration and ranging to the OLT CT 210. Self-calibration
of the transmitter and the receiver may comprise calibrating the
wavelengths of upstream optical signals that the transmitter
transmits and downstream optical signals the receiver receives by
adjusting control parameters including temperature, current, and
voltage on the ONU. After the self-calibration, the wavelength of
the upstream optical signals that the transmitter of the ONU 220
transmits should match the wavelength of the upstream optical
signals that the receiver of the OLT CT 210 receives. Similarly,
the wavelength of the downstream optical signals that the receiver
of the ONU 220 receives should match the downstream wavelength of
the optical signals that the transmitter of the OLT CT 210
transmits.
[0032] The ONU 220 transmits the OLT CT 210 an upstream message
230. The upstream message 230 is a PLOAM message and comprises a
correlation tag that differentiates the ONU 220 from other ONUs.
The correlation tag may represent a unique non-zero number in
various forms. For example, the correlation tag may comprise a
unique non-zero number in a 16-bit field. The unique non-zero
number changes to a different unique non-zero number when the ONU
220 tunes the wavelength, power, or both of the upstream optical
signals.
[0033] The OLT CT 210 receives the upstream message 230, evaluates
the upstream message 230, and transmits a downstream message 240 to
the ONU 220. The evaluation of the upstream message 230 includes
determining if the ONU 220 transmits the upstream signals with
right wavelength and power, if the ONU 220 needs to calibrate more
upstream wavelength channels, and if the ONU 220 is ready to be
activated for operation under the existing control parameters. The
downstream message 240 is also a PLOAM message.
[0034] In one embodiment, the downstream message 240 may be a new
calibration downstream message created by the OLT CT 210. Table 1
describes parameters of the downstream message 240 according to an
embodiment of the disclosure. The downstream message 240 comprises
an unassigned ONU identification (ID), a message type ID, a
sequence number (SeqNo), a vendor-specific serial number, a message
index, a calibration ID, an upstream wavelength channel ID, a
received signal strength indicator (RSSI), a padding, and a message
integrity check. The message index is the correlation tag copied
from the upstream message 230.
[0035] The calibration ID comprises "0" bits and a calibration
status bit. For example, table 1 shows that the calibration ID
comprises 8 bits, 7 "0" bits followed by a calibration status bit.
The calibration status bit is decided based on the evaluation of
the upstream message 230 of the OLT CT 210. The calibration status
bit has a first binary value indicating the ONU 220 should continue
calibration, and a second binary value indicating the ONU 220
should be activated for operation, where the first binary value and
the second binary value are different. In one embodiment, table 1
shows the first binary value is 0 and the second binary value is 1.
In another embodiment, the first binary value may be 1 and the
second binary value may be 0.
[0036] The upstream wavelength channel ID is either the upstream
wavelength channel in which the upstream wavelength is being
calibrated when the calibration status bit has the first binary
value (e.g. 0 as shown in table 1), or the upstream wavelength
channel which is ready for activation when the calibration status
bit has the second binary value (e.g. 1 as shown in table 1). The
RSSI indicates optical power received from the ONU 220 at the OLT
CT 210. The RSSI may be used by the ONU 220 as a reference for
online calibration.
TABLE-US-00001 TABLE 1 The downstream message according to an
embodiment of the disclosure. Field Content Description #1
Unassigned ONU ID 10-bit unassigned ONU-ID. #2 Message Type ID
Message type ID "Calibration". #3 SeqNo Broadcast PLOAM sequence
number. #4 Vendor-ID 32-bit ONU Vendor-ID code, a four-character
combination discovered at SN acquisition. #5 VSSN 32-bit
vendor-specific serial number, a four-byte unsigned integer
discovered at SN acquisition. #6 Message index Index of the
corresponding ONU PLOAM message. #7 Calibration ID 0000 000A A -
Calibration indication, one bit field with the following
significance: A = 0: the ONU should keep on scanning the upstream
wavelength. A = 1: the ONU should stop the calibration process, and
get ready for the activation process. Other values reserved. #8
Upstream wavelength 0000 UUUU channel ID UUUU - Four-bit upstream
wavelength Channel ID, When A = 0, this four-bit Channel ID
indicates which upstream wavelength Channel the upstream wavelength
is in. When A = 1, this four-bit Channel ID indicates which
upstream wavelength Channel the ONU should use for activation. #9
RSSI These two octets are used to indicate the received optical
power at the OLT side from the ONU. #10 Padding Set to 0x00 by the
transmitter; treated as "don't care" by the receiver. #11 MIC
Message integrity check.
[0037] In another embodiment, the downstream message 240 may be a
revised PLOAM message, for example a revised upstream wavelength
channel information (US_WLCH_INFO) PLOAM message or a revised
assign_ONU_ID PLOAM message. Table 2 describes parameters of the
downstream message 240 according to another embodiment of the
disclosure. The downstream message 240 is generated by adding the
message index, the calibration ID, the upstream wavelength channel
ID, and the RSSI to the existing US_WLCH_INFO PLOAM message.
TABLE-US-00002 TABLE 2 The downstream message according to another
embodiment of the disclosure. Field Content Description #1
Unassigned ONU ID Unassigned ONU ID. #2 Message Type ID Message
type ID "US_WLCH_INFO". #3 0x00 Sequence number. #4 Vendor ID The
code set for the Vendor ID is specified in [ATIS-0300220]. The four
characters are mapped into the 4-byte field by taking each
ASCII/ANSI character code and concatenating them. Example:
Vendor_ID = ABCD .fwdarw. Byte 5 = 0x41, Byte 6 = 0x42, Byte 7 =
0x43, Byte 8 = 0x44. #5 VSSN Vendor-specific serial number. #6 UUU0
000O UUU - Three-bit upstream wavelength Channel ID. O - receiving
path indication O = 0, in-band, O = 1, out-of-band. #7 Message
index Index of the corresponding ONU PLOAM message. #8 Calibration
ID 0000 000A A - Calibration indication, one bit field with the
following significance: A = 0: the ONU should keep on scanning the
upstream wavelength. A = 1: the ONU should stop the calibration
process, and get ready for the activation process. Other values
reserved. #9 Upstream wavelength 0000 UUUU channel ID UUUU -
Four-bit upstream wavelength Channel ID, When Octet 15 = 0000 0000,
this four-bit Channel ID indicates which upstream wavelength
Channel the upstream wavelength is in. When Octet 15 = 0000 0001,
this four-bit Channel ID indicates which upstream wavelength
Channel the ONU should turn to. #10 RSSI These two octets are used
to indicate the received optical power at the OLT side from the
ONU. #11 Padding #12 MIC Set to 0x00 by transmitter; treated as
"don't care" by receiver.
[0038] Table 3 describes parameters of the downstream message 240
according to yet another embodiment of the disclosure. The
downstream message 240 is generated by adding the message index,
the calibration ID, the upstream wavelength channel ID, and the
RSSI to the existing assign_ONU_ID PLOAM message. When the
calibration ID is 00000000, the ONU ID should be ignored by the
ONU.
TABLE-US-00003 TABLE 3 The downstream message according to yet
another embodiment of the disclosure. Field Content Description #1
0x03FF 10-bit broadcast ONU-ID. #2 0x03 Message type ID
"Assign_ONU-ID". #3 SeqNo Broadcast PLOAM sequence number. #4 ONU
ID LSB-justified 10-bit assigned ONU-ID value padded with 6 MSB
zeros; range 0-1022 (0x0000-0x03FE). When field #8 is 0, ONU- ID
should be ignored by the ONU. #5 Vendor ID 32-bit ONU Vendor-ID
code, a four-character combination discovered at SN acquisition. #6
VSSN 32-bit vendor-specific serial number, a four-byte unsigned
integer discovered at SN acquisition. #7 Message index Index of the
corresponding ONU PLOAM message. #8 Calibration ID 0000 000A A -
Calibration indication, one bit field with the following
significance: A = 0: the ONU should keep on scanning the upstream
wavelength. A = 1: the ONU should stop the calibration process, and
get ready for the activation process. Other values reserved. #9
Upstream wavelength UUUU - Four-bit upstream wavelength Channel ID,
channel ID When Octet 15 = 0000 0000, this four-bit Channel ID
indicates which upstream wavelength Channel the upstream wavelength
is in. When Octet 15 = 0000 0001, this four-bit Channel ID
indicates which upstream wavelength Channel the ONU should turn to.
#10 RSSI These two octets are used to indicate the received optical
power at the OLT side from the ONU. #11 Padding Set to 0x00 by the
transmitter; treated as "don't care" by the receiver. #12 MIC
Message integrity check.
[0039] FIG. 3 is a flowchart illustrating a method 300 for ONU
online calibration according to an embodiment of the disclosure.
The method 300 is implemented in an OLT CT in order to activate the
ONU. For example, the OLT CT and the ONU may be the OLT CT.sub.1
115.sub.1 and the ONU.sub.1 150.sub.1. In block 310, an upstream
message which comprises a correlation tag, is received from an ONU.
The correlation tag represents a unique number, which
differentiates the ONU from other ONUs. The unique number changes
to a different number when the ONU tunes the wavelength, power, or
both of the upstream optical signals. In block 320, a downstream
message is generated based on the upstream message. The downstream
message comprises the correlation tag. In block 330, the downstream
message is transmitted to the ONU.
[0040] FIG. 4 is a flowchart illustrating another method 400 for
ONU online calibration according to an embodiment of the
disclosure. The method 400 is implemented in an OLT CT in order to
activate the ONU. For example, the OLT CT and the ONU may be the
OLT CT.sub.1 115.sub.1 and the ONU.sub.1 150.sub.1. In block 410,
an upstream message which comprises a correlation tag, is transmit
to an OLT CT. The correlation tag represents a unique number, which
differentiates the ONU from other ONUs. The unique number changes
to a different number when the ONU tunes the wavelength, power, or
both of the upstream optical signals. In block 420, a downstream
message which comprises the correlation tag is received from the
OLT CT.
[0041] While several embodiments have been provided in the present
disclosure, it may be understood that the disclosed systems and
methods might be embodied in many other specific forms without
departing from the spirit or scope of the present disclosure. The
present examples are to be considered as illustrative and not
restrictive, and the intention is not to be limited to the details
given herein. For example, the various elements or components may
be combined or integrated in another system or certain features may
be omitted, or not implemented.
[0042] In addition, techniques, systems, subsystems, and methods
described and illustrated in the various embodiments as discrete or
separate may be combined or integrated with other systems, modules,
techniques, or methods without departing from the scope of the
present disclosure. Other items shown or discussed as coupled or
directly coupled or communicating with each other may be indirectly
coupled or communicating through some interface, device, or
intermediate component whether electrically, mechanically, or
otherwise. Other examples of changes, substitutions, and
alterations are ascertainable by one skilled in the art and may be
made without departing from the spirit and scope disclosed
herein.
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